scribner



(No ModelQ) I 2 Sheets-Sheet 2. C. E. SGRIBNER.

LOOP KEY.

Patented July 29, 1890.

UNITED STATES PATENT OFFICE.

CHARLES ESCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERN ELECTRIC COMPANY, OF SAME PLACE.

LOOP-KEY.

SPECIFICATION forming part of Letters Patent No. 433,046, dated July 29, 1890.

Application filed March 13, 1885- Serial No. 8,762 (No model.)

To all whom it may concern: head Z, which,when forced down, as shown in Be it known that I, CHARLES E. SCRIBNER, Fig. 2, serves as a wedge, forcing said cona citizen of the United States, residing at Chitact-springs apart, disconnecting said springs cago, in the county of Cook and State of Illifrom contact-points d e, while a new connecnois, have invented a certain new and useful tion is formed between the plunger and spring Improvement in Loop-Keys, (Case 92,) of b. I preferably use a cam-lever m, as shown, which the following is a full, clear, concise, to operate the plunger. By throwing the and exact description, reference being had to cam-leverback, as shown in Fig. 2, the plunger the accompanying drawings, forming a part will be forced down and the springs separated, 1c of this specification. as before described. On throwing the cam-le- My loop-key is designed especially for use ver forward the plunger will be lifted by the in connection with the switch-boards of telecoiled spring and the free ends of the contactphone-exchanges for making the connections springs will move toward each other, spring and disconnections between the operators 1) closing upon point cl and spring 0 upon point I 5 outfit and the telephone-lines. e, as shown in Fig. 1.

In the drawings, Figure 1 is a side elevation The contact-springs, as well as the contactof my loop-key or switch mounted upon its points 01 e, as shown in the drawings, are support and ready for use. Fig. 2 is a view mounted on a block at of insulating material, thereof, partially in section, showing the conpreferably hard rubber. The block m may 20 ducting-plunger forced down so as to form be made of any desired length. Ipreferably contact with one of the contact-springs and make it long enough to accommodate several force said springs apart so as to separate them keys. As the plunger is fitted to its socket, from the contact-points upon which they orit moves up and down without side motion, dinarily rest. Fig. 3 is a diagram illustrative and the contact-keys are lifted simultaneously 2 5 of the circuits of the telephone and transmitfrom or closed simultaneously upon contactter in connection with the cords and clearingpoints (I e. As the head of the plunger touches out shutter, showing the clearing-out shutter the free end of spring 1), electrical connection in circuit. is formed between said spring and the socket. Like parts are indicated by similar letters The plunger, as itis forced further down, lifts 0 of reference in the different figures. the springs from contacts cl 6, as before de- The base or support a,upon which my key scribed. It will thus be seen that a continuis mounted, may be the table or shelf at the ity of contact is maintained between the front of the switch-board. The springs or plunger and spring 1) until the springs have contact-pieces band 0 are mounted, as shown, closed upon contact-points d e. 3 5 and insulated from each other, and are so ad- As used in telephone-exchanges, each of the justed as to normally rest in contact with incontactsprings is permanently connected sulated contact-points d and e, respectively. with a different flexible conducting-cord,said The contactrplunger f is normally held cords being provided with ordinary terminal away from the free ends of the contactplugs for insertion in the spring-jacks upon 40 springs by means of the coil-spring g. This the switch-board. o coil-spring is placed about the stem of the The contact-points d c are connected toplunger below the collar it within the metallic gether by a wire, in the circuit of which is socket 1', good electrical connection being placed the operators outfit, consisting of a constantly maintained between the plunger transmitter and receiver. 45 and socket by means of the coil-spring. The plunger, through the medium of the 5 The contact-sprin g c is provided with insusocket, is permanently connected by a wire lation is at its free end. The spring b at its with spring a, and in the circuit of said wire free end is bent, as shown, toward the free is included a clearing-out annunciator. end of spring 0. In my application (Case 93) executed March 50 The plunger is provided with the conical 28, 1885, and filed April 6, 1885, Serial No.

a block of insulating material and forming the terminals of a loop-circuit, of insulated contact-points d and e, against which, respectively, said springs normally rest, and a plunger placed between said springs and provided with a conical head which serves as a wedge to separate the said springs and lift them from contact-points d e, substantially as and for the purpose specified.

3. The combination, with the contactsprings mounted upon the bloek'of insulating material, of the telephone contact-points, the plunger provided with the beveled head, the coiled spring which holds the plunger away from said contact-springs, and the cam-lever, whereby said plunger may be forced down against the free ends of said contact-springs to separate said springs from said contactpoints, thereby lifting said contact-springs from the telephone contact-points, respectively, substantially as described.

In witness whereof I hereunto subscribe my name this 17th day of February, A. D. 1885.

CHARLES E. SCRIBNER.

Witnesses:

GEORGE P. BARTON, F. H. MoCULLooH. 

